- The hotspots are derived from the NOAA satellite and they represent locations with possible fires. Hotspots may go undetected due to cloudy conditions or incomplete satellite pass.
- Reprocessed satellite data will be availed at a later timing. The hotspot information derived from satellite data reprocessed may differ slightly from that received near real-time but reprocessing is necessary for better quality data.
- Hotspot count from year 2019 onwards is based on the NOAA-20 satellite, and for the period from year 2013-2018 is based on the Suomi-NPP satellite.
Frequently Asked Questions
How does the fire detection algorithm work?
Land fires on the ground emit spectral signals that are characterised by higher emissions of mid-infrared radiation. Such thermal anomalies are exploited by fire detection algorithms to determine whether a particular pixel observed by the satellite’s sensor is or is not associated with a forest fire.If a particular pixel is flagged to be a fire, it is indicated as a hotspot. The fire detection algorithm, also referred to as a contextual algorithm, compares the values of suspected fire pixels against a set of absolute thresholds, and with values of surrounding pixels.
Depending on the size and proximity of fires, they may or may not appear as separate hotspots. If the total size of fire detected is of sub-pixel size, it will appear as a single hotspot. As for active fires with size bigger than a pixel, they will appear as multiple hotspots.
It is important to note that a hotspot detected does not always correspond to actual land fires. Other high temperature bodies may also exhibit similar thermal properties as land fires. Examples are gas flares and power plants. The detection of a fire depends on a number of factors. Fires with short lifespan may have started and ended in between satellite passes. Situations which cause some hotspots and smoke haze to escape detection by satellites include cloud cover, fires below forest canopy, and the relative size and temperature of fires being insufficient to mark the fire as a hotspot.